Global and Local winds in Australia

Australia is a huge country located in the Southern Hemisphere. It stretches from 10° - 40° south and 109° - 155° east. Most of the country is located in the Hadley cell, which goes from 0°-30° North/South. The southern part of Australia is located in the Ferrell cell that goes from 30° - 60° North/South. Since most of the country is located in the Hadley cell, most of the country is influenced by trade winds with southeast direction. The southern part, located in the Ferrell cell is influenced by westerlies with northwest direction. Australia is located in a High pressure belt at 30° south, the boundary between trade winds heading towards equator and westerlies heading towards the pole. At this region you have sinking air, which divergent at surface, usually leaving clear skies and sunny weather. This region is called the horse latitude.

The picture above show how the global winds influence Australia. The blue line at 30° south indicates a subtropical high pressure zone, between tropical trade winds from Hadley cell and prevailing westerlies from Ferrell cell. At this point, rising air from equator traveling both north and south, and subsides here. The subsiding air is very dry because it has dropped the moisture and precipitation over the tropics before it reaches this point. Because of the high pressure zone the subsiding air leaves sunny weather with almost no clouds. And the result is a very warm and dry climate, and this is the reason for the Australian desert at the subtropical zone.

The weather in Canberra is usually very dry, but that is not only because of the warm and dry climate from the subtropical high pressure zone. Which I also talked about earlier in one of my blog posts, Canberra is located in a leeward zone. That means the winds usually comes from inland heading towards the coast (see map above). Because of this you get very little precipitation at this area and also a factor for very warm summers and cold winters.

Above is a topography map of Australia. Australia is actually very flat, but there is some mountains as the map shows. The most famous is the Australian Alps, the ridge located southwest on the map. There are several winds associated with mountains like, Foehn and Chinook winds, mountain and valley breezes and Katabatic winds. Mountain and valley breezes are very common at the Australian Alps. At daytime, sun warms the slope of the vallay, causing air to rise and making a valley breeze. The reverse process happens at night, when the same slope cools. Then you have subsiding air going down slope and you have a mountain breeze.

Australia has a coastline all the way around the continent where land and sea breezes are common. Sea breezes are common at daytime, when sun warms the land, making a low pressure zone there. The temperature difference between land and ocean makes the pressure difference. Usually a higher pressure occurs over the ocean, where the temperature is lower than the land. Then the wind goes from high to low pressure as usual, and you have a sea breeze. The reverse process happens at night, when the land cools more quickly than the ocean. Then you have colder temperature at land surface, makes the pressure higher at land than the ocean. Now you have a land breeze going from higher pressure at land to lower pressure over ocean.

Sources: 

ttp://www.geo.arizona.edu/geo5xx/geo527/NewEnglandOrogen/neoindex.html